Combining Volvo's cars with Uber's self-driving system builds on their nearly three-year relationship and comes as Uber's autonomous driving unit has been hit by a lawsuit over trade secrets and the departure of top talent.

A ride services IPO like Lyft one tests the belief of many auto industry insiders that individual auto ownership will wane as people will sell their cars and rely on "mobility services" such as ride services, car share, bike share - and self-driving vehicles.

Uber acknowledged hiring a former Google engineer - now accused of stealing self-driving car technology - despite having received warnings that he was still carrying around some of his former employer's property.